Methods, systems, and computer program products for managing movement of work-in-process materials in an automated manufacturing environment

ABSTRACT

Methods, systems, and computer program products for managing movement of work-in-process materials between processing units in an automated manufacturing environment are provided. A system includes a host system in communication with a work-in-process (WIP) material lot. The system also includes an application executing on the host. The application implements a method that includes tracking a position of the WIP material lot, receiving a list of the processing units designated to be inoperative during a down time, and receiving a start time and a duration of the down time. The method also includes determining a maximum dwell time for each of the designated processing units and scheduling movement of the WIP material lot during an interim between a current time and the start time of the down time based on current position of the work-in-process material lot, the current time, the start time and duration of the down time, and the maximum dwell time.

BACKGROUND OF THE INVENTION

The present disclosure relates generally to automated material handlingsystems and, in particular, to methods, systems, and computer programproducts for managing movement of work-in-process (WIP) materials in anautomated manufacturing environment.

In a production environment, quantities of materials are transportedthrough a defined route in an automated manufacturing line, e.g., amongprocessing units, as well as temporary storage locations (e.g.,stockers) situated within the route where the materials await furthertransport and processing. Oftentimes, there are instances where thematerials sit idle in these storage locations until a productionmachine, or processing unit, is ready to receive them. When there is alarge amount of materials in a given manufacturing line, the localstockers can become filled to capacity and the production area becomesbacked up. Automated material handling systems (AMHSs) provide someassistance in managing the transport of these materials within aproduction area. AMH systems generally consist of material handlingequipment and a material control system. The material handling equipmentmanages the flow of materials, while the control system manages the flowof information relating to these materials. Where an automated materialhandling system (AMHS) is employed, these idle materials are oftenautomatically transferred to central storage when a stocker is full,regardless of whether the materials will be needed by the productionline soon.

When a manufacturing line is shut down, either by a planned maintenance,retooling, or by unforeseen circumstances, the production materials maybe subject to various degrees of degradation. For example, in asemiconductor fabrication facility, certain production materials, suchas chemically treated wafers, if left exposed in a location within theproduction route for a specified period of time, may suffer oxidation orsimilar types of hazards. Depending upon the length of the equipmentshutdown period, the results can be devastating, particularly whenexpensive production materials need to be scrapped as a result of damagedue to environmental exposure. Moreover, the costs of additional cycletime and reduced equipment utilization exacerbate this problem.

What is needed, therefore, is a way to manage the movement of productionmaterials in an automated manufacturing line that preserves theintegrity of the production materials during shut down of the processingequipment in the manufacturing line.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention include systems for managing movement ofwork-in-process materials between processing units in an automatedmanufacturing environment. A system includes a host system incommunication with a work-in-process (WIP) material lot. The system alsoincludes an application executing on the host. The applicationimplements a method that includes tracking a position of the WIPmaterial lot, receiving a list of the processing units designated to beinoperative during a down time, and receiving a start time and aduration of the down time. The method also includes determining amaximum dwell time for each of the designated processing units andscheduling movement of the WIP material lot during an interim between acurrent time and the start time of the down time based on currentposition of the work-in-process material lot, the current time, thestart time and duration of the down time, and the maximum dwell time.

Additional embodiments include a system for managing movement ofwork-in-process (WIP) materials between processing units in an automatedmanufacturing environment. The system includes an automatedmanufacturing line having multiple processing units, at least onework-in-process material lot positioned at a given instant in time at apoint along the automated manufacturing line, the work-in-processmaterial lot including production materials, and a process controllercoupled to the work-in-process material lot. The system also includes ameans for tracking the position of the work-in-process material lot anda means for determining and inputting to the process controller anactual down time having a start time and a duration, and a list of oneor more of the processing units inoperative during the down time. Thesystem also includes a solver product, and a database accessible by thesolver product including information regarding a plurality of maximumdwell times, each of the maximum dwell times associated with one of theprocessing units for which a work-in-process material lot may remain ata given processing unit while maintaining a minimum threshold integrityvalue of the production materials. The solver product is responsive tothe position of the work-in-process material lot, the duration of thedown time, and the maximum dwell time to generate a report identifyingactual dwell time and maximum dwell time for the work-in-processmaterial lot.

Further embodiments include a method for managing movement ofwork-in-process materials between processing units in an automatedmanufacturing environment. The method includes tracking a position ofthe WIP material lot, receiving a list of the processing unitsdesignated to be inoperative during a down time, and receiving a starttime and a duration of the down time. The method also includesdetermining a maximum dwell time for each of the designated processingunits and scheduling movement of the WIP material lot during an interimbetween a current time and the start time of the down time based oncurrent position of the work-in-process material lot, the current time,the start time and duration of the down time, and the maximum dwelltime.

Further embodiments include a computer program product for managingmovement of work-in-process materials between processing units in anautomated manufacturing environment. The computer program productincludes instructions for implementing a method. The method includestracking a position of the WIP material lot, receiving a list of theprocessing units designated to be inoperative during a down time, andreceiving a start time and a duration of the down time. The method alsoincludes determining a maximum dwell time for each of the designatedprocessing units and scheduling movement of the WIP material lot duringan interim between a current time and the start time of the down timebased on current position of the work-in-process material lot, thecurrent time, the start time and duration of the down time, and themaximum dwell time.

Other systems, methods, and/or computer program products according toembodiments will be or become apparent to one with skill in the art uponreview of the following drawings and detailed description. It isintended that all such additional systems, methods, and/or computerprogram products be included within this description, be within thescope of the present invention, and be protected by the accompanyingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 depicts a portion of a system upon which automated WIP movementmanagement functions may be implemented in accordance with exemplaryembodiments; and

FIG. 2 is a flow diagram describing a process for managing movement ofWIP materials in a manufacturing environment in exemplary embodiments.

The detailed description explains the preferred embodiments of theinvention, together with advantages and features, by way of example withreference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments are directed to methods, systems, and computerprogram products for managing work-in-process (WIP) material undergoingprocessing in an automated manufacturing line. The system may be used tomanage movement of WIP materials prior to a planned complete or partialshutdown of the automated manufacturing line. Based on a known positionof the WIP materials along the line, plus knowledge of when the shutdownwill occur, as well as the location where the WIP materials should beheld, or “parked”, during the shutdown in order to minimize any damageto the materials during the shutdown period, and knowledge of how longit will take the WIP material to reach a safe parking location, thesystem generates a plan regarding locations at which specific WIPmaterials should be held prior to the shutdown. In addition, the systemmay generate a report after an occurrence of an unplanned shutdown,providing information regarding the status of WIP materials; forexample, identifying WIP materials that are positioned at a locationwhere damage will occur relatively quickly, and thus which requiresprompt attention.

Turning now to FIG. 1, a portion of a system upon which automated WIPmovement management functions may be implemented in accordance withexemplary embodiments will now be described. The system of FIG. 1includes a host system 102 in communication with manufacturing equipment(104, 106, 108) over one or more networks 110. In exemplary embodiments,the host system 102 is implemented by a manufacturing enterprise thathas adopted enterprise standards, such as SEMI®, or SemiconductorEquipment and Materials International®, headquartered in San Jose,Calif.

The host system 102 executes a variety of business applications utilizedby an enterprise for facilitating the production processes occurring inthe manufacturing environment of FIG. 1. Host system 102 may beimplemented by a computer with a high-powered processor for handling thevolume of production activities occurring in the manufacturingenvironment of FIG. 1. Types of business applications executed by hostsystem 102 may include a manufacturing execution system (MES), automatedmaterial handling system (AMHS), and similar types of software. The AMHSmanages the transport of materials within the manufacturing environmentof FIG. 1 and interfaces with the MES for receiving operations andscheduling information for processing of materials on equipment in themanufacturing area, as well as other functions.

The host system 102 also executes one or more applications forimplementing the automated WIP movement management functions. These oneor more applications are collectively referred to as an automated safeparking application 112.

The manufacturing equipment includes a transport device 104, processequipment, and stocker 108. The manufacturing equipment may bemaintained in one or more production bays that each includes processtools, as well as work-in-process (WIP) materials engaged in, orawaiting, a process or procedure performed by the tools. Materials thatmay be used in manufacturing may include substances, component parts,assemblies, and other items typically found in a manufacturingenvironment. WIP materials refer to those materials that are currentlyundergoing a machine process or en route between machines (e.g.,processing units 106) or production bays. Materials that are awaitingprocessing may be stored in local storage (e.g., local stocker 108). Aninterbay/intrabay transport device (e.g., transport device 104) enablesWIP materials to be conveyed between and within production bays,respectively.

Each of the processing units provides one location within themanufacturing environment of FIG. 1 whereby a specified manufacturingprocess is performed on the WIP materials in accordance with amanufacturing plan. Transport device 104 may be a mechanized groundvehicle such as an automated guided vehicle (AGV) or personal guidedvehicle (PGV), or may be an overhead transport (OHT) device supported bya monorail that transfers WIP materials between and within productionbays.

As indicated above, stocker 108 refers to a temporary storage deviceused to retain materials that are awaiting processing in a manufacturingarea. In a typical manufacturing environment, a transport vehicle (e.g.,transport device 104) retrieves WIP materials from a local stocker(e.g., stocker 108) and transports the materials to the processing unit106 to which the materials have been assigned. These process materialsare assigned to various production bays, some of which materials may beready for processing within minutes and others that may be waiting forhours or days. For example, the materials stored in a local stocker maybe assigned to a current job (e.g., next in line in processing), ashort-term pending job (e.g., ready for processing within minutes orhours), or a long-term pending job (e.g., hours or days). If thescheduled production cycle is interrupted for any period of time, thiscan result in exposure of the materials to environmental hazards withinthe production area, as well as costly degradation of the quality of thematerials.

While only one of each type of equipment is shown in the system of FIG.1, it will be understood that multiple equipment devices may be employedin order to realize the advantages of the exemplary embodiments.

Networks 110 may comprise any type of communications network. Inpreferred embodiments, networks 110 include an Ethernet local areanetwork (LAN).

Host system 102 is in communication with a storage device 114. Storagedevice 114 stores a variety of data used by the host system 102. Storagedevice 114 may be logically addressable to host system 102 for receivingrequests for data and communicating search results to the host system102. One type of data stored in storage device 114 is production data.Production data refers to the specific information used by the AMHS toperform transport activities in accordance with scheduled productionoperations. For example, production data may include tables identifyingeach local stocker, the stockers' current load and capacity, thematerials carried within the stocker, etc. Detailed performance metricsfor stockers may also be stored as part of production data such asrelative throughputs, mean stocker cycle times for materials capacity,peak stocker cycle times for materials, stocker mean times betweenincidents, stocker availability, alarm conditions relating to carrierdrops, weight loads, contamination control, charge build up on carrier,etc. These and other SEMI-derived performance metrics standards may beutilized. Production data may also include process steps formanufacturing processes utilized within the manufacturing area of FIG.1, the status of production activities occurring within production bays,etc.

The storage device 114 may also store transport process jobs. Transportprocess jobs may include work orders or directives that instruct theAMHS to carry out specified operations on candidate materials selectedfor movement.

The storage device 114 also stores maximum dwell times associated withthe processing units for which a work-in-process material lot may remainat a given processing unit while maintaining a minimum thresholdintegrity value of the production materials. The minimum threshold valuemay be determined using any criteria. For example, the minimum thresholdvalue may be determined as a function of the percentage of lossresulting from exposure of the production materials, which is expressedin dollars. Integrity values specify an assessed worth of the productionmaterials, which may be based upon, e.g., costs of their replacement.

The automated safe parking application 112 may include variouscomponents, which collectively perform the automated WIP movementmanagement functions described herein. As shown in the system of FIG. 1,the automated safe parking application 112 executes a process controllerand user interface 116, a WIP tracker 118, a solver 120, and adispatcher 122. The automated safe parking application 112 may be astand-alone application or may be integrated with an MES or AMHS tool.

The process controller is in communication with the WIP materials andthe user interface 116 provides the capability for a user (e.g., arepresentative of the enterprise implementing the host system 102) toinput to the process controller an actual, or projected future, downtime having a start time and a duration, and a list of one or more ofthe processing units (e.g., processing equipment 106) that will beinoperative during the down time. The down time refers to a period oftime in which one or more equipment devices (e.g., process equipment106) will be inoperative; that is, the work station is not processingproduction materials specified in the production plan.

The WIP tracker 118 tracks the position of the WIP materials as they aretransported through the manufacturing area (e.g., from unit to unit,stocker to unit, stocker to stocker, etc.), e.g., via signalingtransmissions between the equipment 104-108 and the WIP tracker 118 andstoring the data in the tables of storage device 114. The solver 120accesses information in the storage device 114, such as maximum dwelltimes, process routes/steps, safe holding points, etc., and isresponsive to the position of the WIP materials, the duration of thedown time, the maximum dwell time, and other information and determineshow and when to schedule movement of the WIP materials accordingly. Thesolver 120 assigns an indicator to each of the WIP materials andtransmits the indicator to the dispatcher 122 for execution. Inalternative exemplary embodiments, the solver 120 is responsive to theposition of the WIP materials, the duration of the down time, themaximum dwell time, and other information to generate a reportidentifying the actual dwell time and maximum dwell time for thematerials.

Turning now to FIG. 2, a flow diagram describing a process for managingmovement of WIP materials in a manufacturing environment will now bedescribed in exemplary embodiments. At step 202, a user of the automatedsafe parking application 112 inputs a list of WIP materials (alsoreferred to as “lots”) to the host system 102 via the user interfacecomponent 116. At step 204, a list of routes with raw process time (RPT)by process steps and with safe holding points are indexed. Each processflow or route defines the processing steps that any particular WIPmaterials will receive that is assigned to that route. The indexing maybe implemented by reading this information in the route and accessingand sorting the information as it is to be used in each of thesubsequent processing steps. The information contains data such as theRPT, safe holding points, and any other pertinent data directlyassociated with the routing of the production materials as it relates toits processing and storage.

The safe holding points refer to locations in the manufacturing areathat are deemed safe for storing the WIP materials. This determinationmay be made by identifying locations that do not pose a threat to theintegrity of the materials when they are located or temporarily storedat the locations.

At step 206, the user indexes a scheduled time of shutdown (e.g., astart time of the shutdown whereby one or more processing units 106 willbe inoperative). At step 208, current XFACTORS for various sectors inthe manufacturing area are indexed. XFACTORS refer to a calculation thatdivides the total cycle time for a lot by the raw process time todetermine the ratio of active processing and wait time to the activeprocess time only. This information is used by the solver 120 todetermine assignment of lots for dispatch priority or hold as describedherein.

At step 210, the transport time for moving each of the lots to the nextnearest identified safe holding point is calculated. At step 212, thefirst lot in the list is selected for review.

At step 214 it is determined whether the lot is currently at a safeholding point. As indicated above, this may be determined by identifyingthe current time, the scheduled shut down start time and duration, theXFACTOR, and a current position of the lot in its route. If the lot isnot currently at a safe holding point at step 214, the lot is assigned adispatch priority indicator at step 222. The dispatch priority indicatorensures that the movement of the lot will be given priority in order tominimize or eliminate degradation to the lot. The dispatch priority maybe implemented by flagging the lot information stored in the storagedevice 114 and tasking the dispatcher 122 to perform the dispatchpriority movement of the lot as indicated in the process route for thelot. Otherwise, if the lot is currently at a safe holding point, thetransport time to the next nearest safe holding is calculated at step216.

At step 218, it is determined whether the time to the nearest safeholding point is greater than the scheduled shutdown start time. If so,this means that the lot is determined to have adequate time to reach thenext nearest safe holding point before the scheduled shut down time. Inthis event, the lot is assigned a stop priority indicator at step 220,reflecting that no further action is required for this lot with respectto the automated safe parking application 112 functions (e.g., the lotis handled according to the processing instructions in the processroute).

If, however, the time to the nearest safe holding point is less than orequal to the scheduled shut down start time, the lot is assigned adispatch priority at step 222 as described above. The processesdescribed with respect to steps 214 to 222 may be repeated for each lotin the list.

It is then determined whether this is the last lot in the list at step224. If not, the next lot in the list is selected at step 226 and theprocess returns to step 214 as described above. Otherwise, the list issent with assigned lot priorities to the dispatcher 122 at host system102 for execution. The dispatcher 122 ensures that lots assigned withpriority dispatch indicators are transported to a safe holding pointprior to the initiation of the shutdown.

In alternative exemplary embodiments, an unexpected disruption of themanufacturing environment may occur, such as a power outage or equipmentbreakdown. In this embodiment, the automated safe parking application112 generates a report upon the occurrence of an unplanned shutdown,providing information regarding the status of the WIP materials, e.g.,identifying WIP materials that are positioned at a processing equipment106 where damage will occur relatively quickly, thereby requiring promptattention.

For example, a report may provide information identifying each of theWIP materials in production, in temporary storage, and en route. Thereport may further list the current locations of each WIP materials asof the time of shutdown, as well as the anticipated integrity valuesover time (e.g., based upon the shut down time period, type ofmaterials, and current locations). In this manner, priorities can bedetermined as to which lots should receive priority treatment when theequipment is back up and running.

As described above, embodiments can be embodied in the form ofcomputer-implemented processes and apparatuses for practicing thoseprocesses. In exemplary embodiments, the invention is embodied incomputer program code executed by one or more network elements.Embodiments include computer program code containing instructionsembodied in tangible media, such as floppy diskettes, CD-ROMs, harddrives, or any other computer-readable storage medium, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Embodimentsinclude computer program code, for example, whether stored in a storagemedium, loaded into and/or executed by a computer, or transmitted oversome transmission medium, such as over electrical wiring or cabling,through fiber optics, or via electromagnetic radiation, wherein, whenthe computer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Whenimplemented on a general-purpose microprocessor, the computer programcode segments configure the microprocessor to create specific logiccircuits.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, the use of the terms first, second, etc. do not denoteany order or importance, but rather the terms first, second, etc. areused to distinguish one element from another. Furthermore, the use ofthe terms a, an, etc. do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced item.

1. A method for managing movement of work-in-process (WIP) materials between processing units in an automated manufacturing environment, comprising: tracking a position of a work-in-process material lot, the work-in-process material lot including production materials; receiving a list of one or more of the processing units designated to be inoperative during a future projected down time; receiving a start time and a duration of the future projected down time; determining a maximum dwell time associated with each of the designated processing units, the maximum dwell time specifying a maximum amount of time the work-in-process material lot may remain at each of the designated processing units while maintaining a minimum threshold integrity value of the production materials; and scheduling movement of the work-in-process material lot during an interim between a current time and the start time of the future projected down time based on a current position of the work-in-process material lot, the current time, the start time and duration of the future projected down time, and the maximum dwell time.
 2. The method of claim 1, wherein scheduling the movement of the work-in-process material lot includes assigning a dispatch priority indicator to the work-in-process material lot when the maximum dwell time is met or exceeded, the method further comprising: transmitting the dispatch priority indicator to a dispatcher for execution.
 3. The method of claim 2, wherein the dispatch priority indicator is operable for expediting movement of the work-in-process material lot to a nearest location in the automated manufacturing line that is determined to be capable of maintaining the minimum threshold integrity value of the production materials.
 4. The method of claim 1, wherein scheduling the movement of the work-in-process material lot includes assigning a stop priority indicator to the work-in-process material lot when the maximum dwell time is not exceeded, the method further comprising: transmitting the stop priority indicator to a dispatcher for execution.
 5. The method of claim 4, wherein the stop priority indicator is operable for maintaining the current position of the work-in-process material lot for the duration of the projected future down time.
 6. The method of claim 1, further comprising: assigning the minimum threshold integrity value to the designated processing units, wherein the minimum threshold integrity value is based on a projected maximum acceptable degradation of the production materials. 